在 PHP 函数中引用类变量作为默认参数

Question

I would like to have a function in my class that has a default parameter so that one can omit the argument if required. I want the default to be a variable stored in my class;

Hi why is this showing error messages in Aptana?

class property{
    private $id;
    function load_data($id = $this->id){
        //...blah blah blah
    }
}

Should I instead use

class property{
    static $id;
    function load_data($id = self::id){
        //...blah blah blah
    }
}

?

Thanks for the help

Answer 1

I'm pretty sure you can't do what you're looking for. Instead you should simply check to see if the argument has a value, and if it doesn't, assign the default value which is the object property.

class property{
    private $id;
    function load_data($id = null){
        $id = (is_null($id)) ? $this->id : $id;
    }
}

Answer 2

You could do this:

class property
{
    private $id;

    function load_data($id = null){

        if (is_null($id)) {
            $id = $this->id;
        }

        //...blah blah blah
    }
}

Answer 3

I know its an old question but I came up on it searching for the same kind of thing and the answer is yes you can do it, as long as you define it as a constant:

class property{
    const $id;
    function load_data($id = self::id){
        //...blah blah blah
    }
}